Human gingiva is being investigated by electron microscopy and tissue culture with the intent of developing new theories about the disease processes of the periodontium. This project is particularly keyed to studies on the biology of the gingiva, especially those facets related to epithelial-connective tissue interactions, changes of the basal lamina, irregularities of the anchoring fibrils, presence of elastic-like filaments in the lamina propria, alterations in the epithelial mitochondria, collagenolysis in vitro and cytodifferentiation in tissue culture.